Over the years, there has been developed a substantial body of patent and other literature directed to the formation and properties of poly(aryl ethers) (hereinafter called "PAE"). Some of the earliest work such as by Bonner, U.S. Pat. No. 3,065,205, involves the electrophilic aromatic substitution (e.g. Friedel-Crafts catalyzed) reaction of aromatic diacylhalides with unsubstituted aromatic compounds such as diphenyl ether. The evolution of this class to a much broader range of PAE's was achieved by Johnson et al., Journal of Polymer Science, A-1, Vol. 5, 1967, pp. 2415-2427, Johnson et al., U.S. Pat. Nos. 4,108,837 and 4,175,175. Johnson et al., show that a very broad range of PAE can be formed by the nucleophilic aromatic substitution (condensation) reaction of an activated aromatic dihalide and an aromatic diol. By this method, Johnson et al. created a host of new PAE's including a broad class of poly(aryl ether ketones), hereinafter called "PAEK's".
In recent years, there has developed a growing interest in PAEK's as evidenced by Dahl, U.S. Pat. No. 3,953,400; Dahl et al., U.S. Pat. No. 3,956,240; Dahl, U.S. Pat. No. 4,247,682; Rose et al., U.S. Pat. No. 4,320,224; Maresca, U.S. Pat. No. 4,339,568; Atwood et al., Polymer, 1981, Vol. 22, August, pp. 1096-1103; Blundell et al., Polymer, 1983 Vol. 24, August, pp. 953-958; Atwood et al., Polymer Preprints, 20, No. 1, April 1979, pp. 191-194; and Rueda et al., Polymer Communications, 1983, Vol. 24, September, pp. 258-260. In the early to mid-1970's, Raychem Corporation commercially introduced a PAEK called STILAN, a polymer whose acronym is PEK, each ether and keto group being separated by 1,4-phenylene units. In 1978, Imperial Chemical Industries PLC (ICI) commercialized a PAEK under the trademark Victrex PEEK. As PAEK is the acronym of poly(aryl ether ketone), PEEK is the acronym of poly(ether ether ketone) in which the 1,4-phenylene units in the structure are assumed.
Thus, PAEKs are well known; they can be synthesized from a variety of starting materials; and they can be made with different melting temperatures and molecular weights. The PAEKs are crystalline, and as shown by the Dahl and Dahl et al. patents, supra, at sufficiently high molecular weights they can be tough, i.e., they exhibit high values (&gt;50 ft-lb/in.sup.2) in the tensile impact test (ASTM D-1822). They have potential for a wide variety of uses, but because of the significant cost to manufacture them, they are expensive polymers. Their favorable properties class them in the upper bracket of engineering polymers.
PAEKs may be produced by the Friedel-Crafts catalyzed reaction of aromatic diacylhalides with unsubstituted aromatic compounds such as diphenyl ether as described in, for example, U.S. Pat. No. 3,065,205. These processes are generally inexpensive processes; however, the polymers produced by these processes have been stated by Dahl et al., supra, to be brittle and thermally unstable. The Dahl patents, supra, allegedly depict more expensive processes for making superior PAEKs by Friedel-Crafts catalysis. In contrast, PAEKs such as PEEK made by nucleophilic aromatic substitution reactions are produced from expensive starting fluoro monomers and thus would be classed as expensive polymers.
In all of the above described U.S. Patents, the copolymers that are described are random or ordered copolymers characterized in that all of the repeat units of the polymer are derived from monomers and are typically distributed randomly along the polymeric chains.
European Patent Application No. 125,816, filed Apr. 19, 1984, based for priority upon British patent Application No. 8,313,110, filed May 12, 1983, is directed to a method for increasing the molecular weight by melt polymerization of a poly(aryl ether) such as PEEK.
The process of European Patent Application No. 125,816, provides a basis by melt polymerization above the crystalline melting point of the poly(aryl ether) to increase the molecular weight by chain extension of polymer blocks. The application theorizes that the procedure can be used for making the block copolymers described in U.S. Pat. Nos. 4,052,365 and 4,268,635. Implicit problems associated in the process of this application are the difficulty in controlling the molecular weight of the resulting polymer and/or limiting isomerization and the problems associated with branching. The process of this European application would appear to be advantageous in making composites where the linearity and solution properties of the final polymer are not so critical.
PAEK block copolymers have been described in U.S. Pat. Nos. 4,052,365 and 4,268,635. U.S. Pat. No. 4,052,365 describes random or block copolymers having repeating units of the structure --Ar--O--Ar--CO-- and --Ar--O--Ar--SO.sub.2 --. The patent states that these block copolymers are crystalline. U.S. Pat. No. 4,268,635 describes a process for preparing polymers containing --Ar--O--Ar--CO-- and --Ar--O--Ar--SO.sub.2 -- units which the patentee believes to contain block structures. The patent states that the polymers are crystalline and exhibit improved high temperature properties compared with totally random copolymers of similar composition. However, the block copolymers in said patents require units with --SO.sub.2 -- linkages. The --SO.sub.2 -- linkage tends to break up the crystallinity of the polymer which results in inferior properties as compared to polymers which do not contain the --SO.sub.2 -- linkage but have ether and/or keto groups instead. Due to the amorphous nature of the sulfonyl containing component used in making these prior art block copolymers, lower rates of crystallization are induced and hence, their commercial utility is less than desirable. The --SO.sub.2 -- component so adversely affects the crystallinity properties that there is a maximum limit in the T.sub.m, far below that for the block polymers of this invention. A further deficiency of these prior art block copolymers is that they cannot be used to form compatible blends with other PAEKs.
U.S. patent application, Ser. No. 729,580 filed on May 2, 1985, in the names of R. A. Clendinning et al., titled "Block Polymers Containing a Poly(Aryl Ether Ketone) and Methods for Their Production", commonly assigned, describes a family of novel aryl ether ketone block copolymers. The blocks of the subject patent application contain essentially ether groups (--O--) joined to keto groups (--CO--) through 1,4-phenylene groups. The block copolymers in question are tough materials, that are easy to fabricate; their thermal and chemical resistance are excellent. However, their glass transition temperatures are rather low for some applications; they are generally in the range of about 150.degree. to about 160.degree. C. In some applications, such as in composites for example, a highly stable and tough matrix having a high glass transition temperature is required. This is due to the fact that polymers, even crystalline polymers, exhibit an excessive loss of modulus, strength and creep resistance above their Tg's. This loss in properties may not be acceptable in cases where the materials are to be used as thermoplastic matrix resins. Hence, the preparation of poly(aryl ether ketones) combining their generally excellent properties with high glass transition temperatures is of great practical importance. Such high Tg block and extended copolymers are described herein.